割缝与压裂协同增透技术参数数值模拟与试验

Numerical simulation parameters and test of cutting and fracturing collaboration permeability-increasing technology

针对古汉山矿低透气性煤层穿层抽采钻孔卸压不充分的问题,提出了割缝与压裂协同增透技术,基于弹性断裂力学和Biot经典渗流力学理论,采用数值模拟的方法,分析了割缝钻孔与压裂钻孔协同布置时不同条件下压裂裂缝扩展规律,确定割缝钻孔与压裂钻孔水平距离为4 m时压裂效果较好,缝槽相对于水平方向的倾角应避免为45°,割缝钻孔形成的缝槽可以控制压裂裂缝的扩展方向,裂缝影响范围内应力由约8 MPa下降至4 MPa以内。现场试验表明,距割缝钻孔2 m以内的煤体发生了位移,协同割缝钻孔的瓦斯抽采纯量是割缝钻孔的2.3倍,是普通钻孔的7.8倍,协同压裂钻孔的瓦斯抽采纯量是压裂钻孔的2.1倍,普通钻孔的5倍,瓦斯抽采效率显著提高。

For the pressure relief inadequacy problem of drainaging holes through coal in the low permeability in Guhanshan Coal Mine,the technology of increasing permeability by collaborative cutting and fracturing was proposed.Based on the elastic fracture mechanics and Biot classic percolation mechanics theory,the fracturing propagation law in different conditions was analyzed by using numerical simulation method,it was determined that the fracturing effect was better when the horizon distance between the slot and the fracture bore was 4 m,angle relative to the horizontal direction of the slot should be avoided for 45°,the slots by hydraulic slotting can control the extension direction of slots by hydraulic fracturing,the stress decreased from about 8 MPa to 4 MPa within the scope of influence by slotting. Field test results show that,after adopting the technical measures,the maximum distance between the movement coal and slotted hole was 2 m,the gas extraction flow of the collaborative slotting drilling increases to 2. 3 times of the slotting drilling,and 7. 8 times of the ordinary drilling,the gas extraction flow of the collaborative hydraulic drilling increases to2. 1 times of the hydraulic drilling,and 5 times of the ordinary drilling,increase the efficiency of the extraction.